• Most ROVs are equipped with at least a video camera and lights. • Additional equipment: sonars, magnetometers, a still camera, a manipulator or cutting arm, grabbing arms, water samplers, and instruments that measure water clarity, light penetration and temperature
9
Lifting pipe
Diameter? Concentration? Velocity?
10
Outline
• Seabed Exploration
• Deep sea mining system
• Research on lifting pipe
Force of nodules in Pipe
• Gravity • Buoyancy • Drag force
C drag coefficient (shape and Re),A cross sectional area
Fd C f V 2 A / 2
• Pressure gradient force • Basset force: lagging boundary layer development with changing relative velocity (acceleration) of bodies moving through a fluid • Saffman lift force: Velocity gradient, from the side with low velocity to high • Magnus force https:///watch?v=rcjMs82PAWg
Deep sea Mining
Outline
• Seabed Exploration
• Deep sea mining system
• Research on lifting pipe
2
Seabed Exploration and Mapping(1)
• Single-Beam Echo Sounder (SBES)_water depth • Multi-Beam Echo Sounder (MBES)_ sending sound waves at various angles ----- comprehensive information on the bottom surface.
8
Deep sea mining system
• A prime candidate for the lift system is one which hydraulically transports the nodules as a slurry through a lift pipe string, connecting the collector on the seafloor to the mining vessel on the surface[J.Q. Burns1979]
17
18
Local concentration:
16Βιβλιοθήκη Other research area
• Dynamic behavior of pipe • The influence of dynamic behavior of pipe on inner flow • Erosion of the pipe • Unsteady flow and block of pipe • Air lifting system
Seafloor Massive sulfide
Ni 49 850 Cu 511 765
Cobalt nodule
Co 2.7 170
7
Deep sea miner
Source: /2013/07/deep-sea-mining-this-shit-just-got-real/
6
Outline
• Seabed Exploration
• Deep sea mining system
• Research on lifting pipe
Mineral from the Seafloor
Manganese nodule
Unit(MT) Land(1983) Seafloor Mn 1,835 24,650
Source: (Jerzy Sobota,2006)
12
Variations of nodules concentration and velocity
Source:Jerzy Sobota,2005
13
Head loss
Source:Jerzy Sobota,2007
14
Slip velocity
11
Loop in Lab
Gamma radiation: particles absorption of gamma radiation Labeled water: radioactive substance distribute in water, particles replaced water, make measurement more sensitive Labeled stone: stone with radioactive---velocity of particles, symbol for circulate
Source:Jerzy Sobota,2007
Slip velocity: difference between a liquid velocity and solid vslip vwater vparticle velocity:
15
Local concentration
Lagging effect:concentration in the pipe is greater than the entrance Particles weight is the same at the entrance and outlet of lifting pipe
AvmCv p ACvl v p p ACvl (v f vs ) p
A(1 Cv )vm p A(1 Cvl )v f f
v v 1 1 v Cvl [1 m ] [ ( m 1)2 Cv m ] 2 vs 4 vs vs
For water:
5
Seabed Exploration and Mapping(4)
• autonomous underwater vehicle (AUV)---robot which travels underwater without requiring input from an operator • echo sounders and various measurement sensors
3
Seabed Exploration and Mapping(2)
• Controlled-source electromagnetic (CSEM) surveying • Magneto telluric (MT) surveying
4
Seabed Exploration and Mapping(3)